A Secure Proxy-Protected Signature Scheme Based on the Strong RSA Assumption

Executive Summary

Ordinary Signature Scheme is one of the most important primitive of public-key cryptography. As a variation of ordinary digital signature scheme, a proxy signature allows a designated person, called a proxy signer, to sign the message on behalf of the original signer. A proxy signature now-a-days is an active research topic, which attracts many researchers' attentions. However, most proposed proxy signature schemes are based on discrete logarithm and pairings. A few proxy signature schemes are built based on RSA assumption and factoring problems. To the best of the authors' knowledge, this is the first proxy-protected signature scheme based on the strong RSA assumption, which meets the security requirement of the proxy signature. The proposed scheme is existential unforgeable against adaptive chosen message attacks.